a. Field of the Invention
The present invention relates generally to submersible vessels, and, more particularly, to a wind-powered submersible vessel having wing and keel assemblies that are retractable for submerged operation of the vessel.
b. Related Art
Submersible vessels are waterborne craft capable of surfaced or submerged operation, in a marine environment or other body of water. As is well known, submersible vessels enjoy many advantages for both military and civilian functions, including reduced detectability, avoidance of adverse weather and surface traffic, and the ability to approach/investigate underwater targets, amongst others.
Historically, submersible vessels have taken the form of manned submarines, most commonly using diesel electric or nuclear propulsion systems. The construction and operating costs inherent in manned submarines, in combination with the size required to accommodate the personnel and machinery, have caused them to be restricted mainly to naval use, and even then to only a few of the many potential missions for submersible vessels. For example, manned naval submarines have long been successful in anti-ship and ballistic-missile submarine missions, but their high cost and large size have counted against them for other missions such as long-term surveillance, mine hunting and inshore/shallow water operations, for example. Unfilled potential for submersible vessels also exists in commercial and civilian government realms, such as oil exploration, fisheries monitoring and law enforcement roles, for example.
Recent advances in electronics and controls have opened new horizons for submersible vessels, including increased possibilities for autonomous, unmanned operation. Similar to unmanned aerial vehicles (UAVs), the absence of human support systems allows the vessel to be much smaller and vastly less expensive and, in the case of a seaborne vessel, to have the possibility of virtually unlimited on-station time. These factors in turn open the door for submersible vessels to perform a wide range of missions for which they were not previously viable.
However, certain challenges remain. For example, even in the absence of human support systems there is a need for electrical power, e.g., for the guidance and electronic sensor/communication systems typically necessary for the craft to perform its mission. Similarly, there is a continuing need for propulsion, whether to investigate/intercept targets or to simply proceed on a course/speed or maintain a position in seaway, but with a heightened need that the means of propulsion be both compact and inexpensive in nature. Potentially autonomous operation also means that such systems need to be reliable and capable of operation with little or no maintenance or other human intervention.
An added challenge is that such a craft to be able to function efficiently in both surfaced and submerged modes it must satisfy somewhat conflicting requirements. To operate effectively when surfaced, the craft must have a configuration that enables it to achieve satisfactory stability and control when subjected to wind and wave action. When submerged, the craft is usually less subject to wind/wave action, but in turn it becomes important that the craft have a hydrodynamically “clean” configuration and minimal drag such that it can travel and maneuver underwater in an efficient manner.
Yet another factor, mundane yet nevertheless important, is that an unmanned submersible vessel (similar to the case with a UAV) will most typically be transported to an operating area onboard a parent vessel, possibly in combination with other units, as opposed to transiting independently from a remote port. Consequently, there is a need that the submersible vessel be readily configurable in a compact form for transportation, preferably being able to fit within a standardized shipping container such as a “CONEX” box. Similarly, there is a need that the vessel be simple and safe to deploy once it is in the mission area, and that it be able to withstand the handling involved in launching and/or recovery without incurring damage. It is also important that the design and construction of such a vessel provide it with strength, durability and survivability adequate to meet the requirements of its intended purpose, for example, to withstand adverse environmental conditions or impact/shock incurred in a military mission.